Until the arrival of the red-white-gold Gold Leaf livery, Lotus' works team colours were always green with a yellow stripe. A narrow yellow stripe (Lotus 25, Lotus 33), or a large one involving the car's nose (Lotus 49, Lotus 43-BRM, Lotus 38 Indycar, etc.).
But, occasionally they ran all-green cars, without the yellow stripe. I remember, for example imegas of all-green Lotuses in the 1962 Dutch Grand Prix, or in the 1965 Grand Prix de Pau Formula 2, etc.
There is a reason why they changed colours?